In the fields of pisciculture and aquatic resource management, it is often necessary to perform routine fish handling operations on a large number of live fish. Examples of these operations include sorting fish by size, automated vaccinations, and fish tagging/marking. When performing any of these operations, it is typically desirable that the fish be separated from each other. In addition, separating fish may be especially desirable in order to allow fish to be, e.g., automatically or electronically counted. Indeed, automatic fish counting primarily depends upon the separation of individual fish, rather than on their orientation, as they pass a point at which they are detected and counted. Separation between fish is important in automatic counting operations because counting mechanisms may not be able to distinguish between (and therefore accurately count) fish that are overlapped as they move past the counting mechanism.
Various devices are known for handling live fish prior to a given operation. One such type of device are employed to orient live fish prior to a given operation. For instance, U.S. Pat. No. 5,816,196 (hereinafter “the '196 patent”) describes a device and method for volitionally orienting fish. The '196 patent is incorporated by reference herein as fully as if set forth in its entirety. FIG. 1 illustrates the device described in the '196 patent. Specifically, FIG. 1 illustrates a vessel 1 with a lower interior surface 2 and an apertured end 3. The apertured end 3 contains an exit aperture 4. The exit aperture 4 is generally of a size slightly wider than the fish to be  oriented. The vessel 1 contains water and receives the fish that it are desired to oriented. The supply of fish to be oriented is introduced into the vessel 1 through a supply channel 14, e.g., a supply tank, a net, a second fish handling device, etc. A flow F of water in the vessel 1 is generated in a direction away from the apertured end 3, such as by introducing water through the flow apertures 6 and directed toward the side 9 of the vessel 1 located opposite the apertured end 3. The lower interior surface 2 of the vessel 1 is tilted by placing blocks 15 underneath the lower interior surface 2 proximate to the apertured end 3, so as to facilitate the movement of water in a direction away from the apertured end 3. The flow F away from the apertured end 3 is of sufficient strength so that any fish exiting the vessel 1 through the exit aperture 4 must swim against the flow F in order to pass through the exit aperture 4, thus resulting in the fish having a head-first, dorsal-side-up orientation. The fish are guided towards the exit aperture 4 by slanted walls 7. However, while the device illustrated in FIG. 1, and other conventional fish orienting devices like it, are useful for orienting fish in the head-first, dorsal-side-up orientation, there is still a need to better and more reliably separate the fish.
There are some conventional devices that operate to automatically count fish. For instance, one example of an automatic fish counting mechanism is the “Bioscanner” by Vaki Aquaculture Systems Ltd. of Reykjavik, Iceland. The Bioscanner system includes two acrylic V-shaped channels that are connected to a basin where fish are gathered. Water is pumped into the V-shaped channels from the basin, which is tilted toward the inlets of the channels. The fish in the basin are flushed down the channels. All of the water in this process flows into the channels. At a given distance further down the channels from the channel inlets, the channels narrow to the approximate width of a single fish and curve sharply downward. The effect of the downward curving channels is to accelerate the fish as they pass through the channels, thereby increasing the separation between individual fish or, if the fish were overlapped when they entered the channels, causing the fish to be separated. Counting scanners are located at the bottom of the V-shaped channels and operate to count the fish as they pass by the scanners. However, this and other  conventional devices for separating fish do not ensure adequate separation between fish.
Thus, there is a need to provide a system and method for controlling fish flow that ensures adequate separation between fish.
It is therefore an object of the present invention to provide a system and method for controlling fish flow that ensures adequate separation between fish.